chore: improve version mismatch error

packages/playwright/src/index.ts

@@ -18,11 +18,12 @@ import fs from 'fs';
 import path from 'path';
 
 import * as playwrightLibrary from 'playwright-core';
-import { setBoxedStackPrefixes, createGuid, currentZone, debugMode, jsonStringifyForceASCII, asLocatorDescription, renderTitleForCall, getActionGroup } from 'playwright-core/lib/utils';
+import { createGuid, currentZone, debugMode, jsonStringifyForceASCII, asLocatorDescription, renderTitleForCall, getActionGroup } from 'playwright-core/lib/utils';
 
 import { currentTestInfo } from './common/globals';
 import { rootTestType } from './common/testType';
 import { runBrowserBackendAtEnd } from './mcp/test/browserBackend';
+import { initPlaywrightTest } from './util';
 
 import type { Fixtures, PlaywrightTestArgs, PlaywrightTestOptions, PlaywrightWorkerArgs, PlaywrightWorkerOptions, ScreenshotMode, TestInfo, TestType, VideoMode } from '../types/test';
 import type { ContextReuseMode } from './common/config';
@@ -39,19 +40,7 @@ import type { BrowserContext, BrowserContextOptions, LaunchOptions, Page, Tracin
 export { expect } from './matchers/expect';
 export const _baseTest: TestType<{}, {}> = rootTestType.test;
 
-setBoxedStackPrefixes([path.dirname(require.resolve('../package.json'))]);
-
-if ((process as any)['__pw_initiator__']) {
-  const originalStackTraceLimit = Error.stackTraceLimit;
-  Error.stackTraceLimit = 200;
-  try {
-    throw new Error('Requiring @playwright/test second time, \nFirst:\n' + (process as any)['__pw_initiator__'] + '\n\nSecond: ');
-  } finally {
-    Error.stackTraceLimit = originalStackTraceLimit;
-  }
-} else {
-  (process as any)['__pw_initiator__'] = new Error().stack;
-}
+initPlaywrightTest('Importing @playwright/test');
 
 type TestFixtures = PlaywrightTestArgs & PlaywrightTestOptions & {
   _combinedContextOptions: BrowserContextOptions,

packages/playwright/src/mcp/test/testContext.ts

@@ -93,7 +93,7 @@ export class TestContext {
   async createTestRunner(): Promise<TestRunner> {
     if (this._testRunner)
       await this._testRunner.stopTests();
-    const testRunner = new TestRunner(this.configLocation!, {});
+    const testRunner = new TestRunner(this.configLocation!, {}, 'Playwright Agent');
     await testRunner.initialize({});
     this._testRunner = testRunner;
     testRunner.on(TestRunnerEvent.TestFilesChanged, testFiles => {

packages/playwright/src/program.ts

@@ -39,6 +39,7 @@ import { ensureSeedTest, seedProject } from './mcp/test/seed';
 import { decorateCommand } from './mcp/program';
 import { setupExitWatchdog } from './mcp/browser/watchdog';
 import { initClaudeCodeRepo, initOpencodeRepo, initVSCodeRepo } from './agents/generateAgents';
+import { initPlaywrightTest } from './util';
 
 import type { ConfigCLIOverrides } from './common/ipc';
 import type { TraceMode } from '../types/test';
@@ -86,7 +87,7 @@ function addClearCacheCommand(program: Command) {
   command.description('clears build and test caches');
   command.option('-c, --config <file>', `Configuration file, or a test directory with optional "playwright.config.{m,c}?{js,ts}"`);
   command.action(async opts => {
-    const runner = new TestRunner(resolveConfigLocation(opts.config), {});
+    const runner = new TestRunner(resolveConfigLocation(opts.config), {}, 'Playwright CLI');
     const { status } = await runner.clearCache(createErrorCollectingReporter(terminalScreen));
     const exitCode = status === 'interrupted' ? 130 : (status === 'passed' ? 0 : 1);
     gracefullyProcessExitDoNotHang(exitCode);
@@ -98,7 +99,7 @@ function addDevServerCommand(program: Command) {
   command.description('start dev server');
   command.option('-c, --config <file>', `Configuration file, or a test directory with optional "playwright.config.{m,c}?{js,ts}"`);
   command.action(async options => {
-    const runner = new TestRunner(resolveConfigLocation(options.config), {});
+    const runner = new TestRunner(resolveConfigLocation(options.config), {}, 'Playwright CLI');
     await runner.startDevServer(createErrorCollectingReporter(terminalScreen), 'in-process');
   });
 }
@@ -163,6 +164,7 @@ function addTestMCPServerCommand(program: Command) {
   command.option('--port <port>', 'port to listen on for SSE transport.');
   command.action(async options => {
     setupExitWatchdog();
+    initPlaywrightTest('Playwright Agent');
     const backendFactory: ServerBackendFactory = {
       name: 'Playwright Test Runner',
       nameInConfig: 'playwright-test-runner',
@@ -206,6 +208,7 @@ function addInitAgentsCommand(program: Command) {
 }
 
 async function runTests(args: string[], opts: { [key: string]: any }) {
+  initPlaywrightTest('Playwright CLI');
   await startProfiling();
   const cliOverrides = overridesFromOptions(opts);
 
@@ -268,6 +271,7 @@ async function runTests(args: string[], opts: { [key: string]: any }) {
 }
 
 async function runTestServer(opts: { [key: string]: any }) {
+  initPlaywrightTest('Playwright CLI');
   const host = opts.host || 'localhost';
   const port = opts.port ? +opts.port : 0;
   const status = await testServer.runTestServer(opts.config, { }, { host, port });
@@ -276,6 +280,7 @@ async function runTestServer(opts: { [key: string]: any }) {
 }
 
 async function mergeReports(reportDir: string | undefined, opts: { [key: string]: any }) {
+  initPlaywrightTest('Playwright CLI');
   const configFile = opts.config;
   const config = configFile ? await loadConfigFromFile(configFile) : await loadEmptyConfigForMergeReports();
 

packages/playwright/src/runner/testRunner.ts

@@ -29,7 +29,7 @@ import { webServerPluginsForConfig } from '../plugins/webServerPlugin';
 import { internalScreen } from '../reporters/base';
 import { InternalReporter } from '../reporters/internalReporter';
 import { affectedTestFiles, collectAffectedTestFiles, dependenciesForTestFile } from '../transform/compilationCache';
-import { serializeError } from '../util';
+import { initPlaywrightTest, serializeError } from '../util';
 import { createErrorCollectingReporter, createReporters } from './reporters';
 import { TestRun, createApplyRebaselinesTask, createClearCacheTask, createGlobalSetupTasks, createListFilesTask, createLoadTask, createPluginSetupTasks, createReportBeginTask, createRunTestsTasks, createStartDevServerTask, runTasks, runTasksDeferCleanup } from './tasks';
 import { LastRunReporter } from './lastRun';
@@ -97,7 +97,8 @@ export class TestRunner extends EventEmitter<TestRunnerEventMap> {
   private _watchTestDirs = false;
   private _populateDependenciesOnList = false;
 
-  constructor(configLocation: ConfigLocation, configCLIOverrides: ConfigCLIOverrides) {
+  constructor(configLocation: ConfigLocation, configCLIOverrides: ConfigCLIOverrides, initiator: string) {
+    initPlaywrightTest(initiator);
     super();
     this.configLocation = configLocation;
     this._configCLIOverrides = configCLIOverrides;

packages/playwright/src/runner/testServer.ts

@@ -94,7 +94,7 @@ export class TestServerDispatcher implements TestServerInterface {
   readonly _dispatchEvent: TestServerInterfaceEventEmitters['dispatchEvent'];
 
   constructor(configLocation: ConfigLocation, configCLIOverrides: ConfigCLIOverrides) {
-    this._testRunner = new TestRunner(configLocation, configCLIOverrides);
+    this._testRunner = new TestRunner(configLocation, configCLIOverrides, 'VSCode extension');
     this.transport = {
       onconnect: () => {},
       dispatch: (method, params) => (this as any)[method](params),

packages/playwright/src/util.ts

@@ -19,7 +19,7 @@ import path from 'path';
 import url from 'url';
 import util from 'util';
 
-import { parseStackFrame, sanitizeForFilePath, calculateSha1, isRegExp, isString, stringifyStackFrames } from 'playwright-core/lib/utils';
+import { setBoxedStackPrefixes, parseStackFrame, sanitizeForFilePath, calculateSha1, isRegExp, isString, stringifyStackFrames } from 'playwright-core/lib/utils';
 import { debug, mime, minimatch } from 'playwright-core/lib/utilsBundle';
 
 import type { Location } from './../types/testReporter';
@@ -31,6 +31,35 @@ import type { TestCase } from './common/test';
 const PLAYWRIGHT_TEST_PATH = path.join(__dirname, '..');
 const PLAYWRIGHT_CORE_PATH = path.dirname(require.resolve('playwright-core/package.json'));
 
+export function initPlaywrightTest(initiator: string) {
+  setBoxedStackPrefixes([path.dirname(require.resolve('../package.json'))]);
+
+  initiator = `  ${initiator}\n  v${require('../package.json').version} at ${PLAYWRIGHT_TEST_PATH}`;
+
+  if ((process as any)['__pw_initiator_path__'] === PLAYWRIGHT_TEST_PATH) {
+    // Same version of Playwright, update the initiator.
+    (process as any)['__pw_initiator__'] = initiator;
+    return;
+  }
+
+  if ((process as any)['__pw_initiator__']) {
+    // Different version of Playwright, throw.
+    const error = new Error([
+      'Mixing two versions of Playwright:',
+      '',
+      (process as any)['__pw_initiator__'],
+      '',
+      initiator,
+    ].join('\n'));
+    error.stack = 'Error: ' + error.message;
+    throw error;
+  }
+
+  // First-time import, set up the initiator.
+  (process as any)['__pw_initiator_path__'] = PLAYWRIGHT_TEST_PATH;
+  (process as any)['__pw_initiator__'] = initiator;
+}
+
 export function filterStackTrace(e: Error): { message: string, stack: string, cause?: ReturnType<typeof filterStackTrace> } {
   const name = e.name ? e.name + ': ' : '';
   const cause = e.cause instanceof Error ? filterStackTrace(e.cause) : undefined;